As shown in FIG. 1, a prior art door bolt has a slide bar seat 1 fastened to the edge of a door, a slide bar 3 disposed in an axial hole 4 of the slide bar seat it and a slide bar retainer seat 5 fastened to a door jamb 6. The slide bar retainer seat 5 is provided with a retaining hole 7, which must be coaxial with the slide bar 3. However, such coaxial arrangement of the slide bar 3 and the retaining hole 7 can be often changed by the displacement of the slide bar seat 1. As a result, the door bolt is useless. Such a displacement of the slide bar seat 1 takes place when the hinged door, to which the slide bar seat 1 is fastened, is caused to diplace horizontally and vertically after a prolonged use of the hinged door.